Review article: A comprehensive review of compound flooding literature with a focus on coastal and estuarine regions

Flooding is the costliest and most common hazard worldwide (Bevere and Remondi, 2022; Mishra et al., 2022; Rentschler et al., 2022) and can lead to a wide range of environmental, economic, and social repercussions. Over 1.8 billion people, almost a quarter (23 %) of the world's population, are exposed to 1-in-100-year flooding (Rentschler et al., 2022). The vast majority (89 %) of these people live in low- and middle-income countries, and socially vulnerable communities are disproportionately at risk. Since 1980, global floods have caused over 250 000 fatalities and USD 1 trillion in losses.

Understanding Compound Flooding

Compound flooding, where the combination or successive occurrence of two or more flood drivers leads to a greater impact, can exacerbate the adverse consequences of flooding, particularly in coastal–estuarine regions. This paper, authored by Joshua Green, Ivan D. Haigh, Niall Quinn, Jeff Neal, and others, reviews the practices and trends in coastal–estuarine compound flood research and synthesizes regional to global findings.

A systematic review is employed to construct a literature database of 279 studies relevant to compound flooding in a coastal–estuarine context. This review explores the types of compound flood events and their mechanistic processes, and it synthesizes terminology throughout the literature.

Key Drivers and Environmental Conditions

According to the research, the following factors are essential to understanding flood compounding:

  • Six flood drivers: fluvial, pluvial, coastal, groundwater, damming/dam failure, and tsunami.
  • Five precursor events and environmental conditions: soil moisture, snow, temp/heat, fire, and drought.

Research Methodology and Future Implications

This review summarizes research methodology and study application trends, as well as considers the influences of climate change and urban environments. Finally, this review highlights knowledge gaps in compound flood research and discusses the implications on future practices.

Recommendations for Future Research

  1. Adopt consistent terminology and approaches.
  2. Expand the geographic coverage of research.
  3. Pursue more inter-comparison projects.
  4. Develop modelling frameworks that better couple dynamic Earth systems.
  5. Design urban and coastal infrastructure with compounding in mind.